An adjustable vibration isolator for limiting transfer of vibrations from a first element to a second element coupled to the first element. The isolator includes conical disc spring members, each having a first end including a central opening, a central axis, and a second end opposite the first end. The second end includes an outer edge of the spring member. A spacer is coupled to each spring member so as to enable a transfer of forces between the spring member and the spacer. Spring member deflection resistance mechanisms are operable to adjustably resist movement of the outer edges of the spring members in directions radially outwardly during loading of the spring members. Resistance of movement of the outer edges of the spring members enables control of a force required to deflect the spring members, and control of the force-deflection curve of the vibration isolator.